Mason is cool as he looks at us. ‘I’m afraid I’m not sure what you’re getting at, Detective Inspector. What contents of which cellar?’

‘The cellar in the converted farm buildings just in front of where you land your helicopter.’ As I speak, something flickers across his face.

‘I know the buildings.’ His voice is calm, but he frowns. ‘But I don’t keep anything in there. I was going to do them up as holiday rentals. But as you obviously know, I’ve decided to sell.’

‘As you’re aware,’ I go on, ‘walls have been built leaving a space that’s unaccounted for on the floor plan. The door is around the back. We found it.’ I pause, watching Mason closely. ‘The key wasn’t among those you left with the estate agent, so we broke in. It was obvious from the floorboards that some had recently been replaced. When we lifted them, we found a staircase.’

There’s a look of incredulity on Mason’s face. ‘This is news to me, Detective Sergeant. Did you find anything?’

‘Enough of this charade.’ The DI’s voice is full of contempt. ‘You know full well what was down there. We have witnesses, Mr Mason, who will testify about the business you encourage people to invest in, before blackmailing them when they find out children are involved and they want their money back. James Hampton, for one.’

As Mason visibly pales, the DI goes on. ‘We’re currently matching your fingerprints with those we’ve found on various items of computer hardware found in your cellar. I’d say it’s a matter of mere minutes before we have proof.’ Still studying Mason, the DI gets up. ‘We’ll take a short break now, and carry on once we have those fingerprints confirmed.’

*

When we reconvene outside the door of the interview room ten minutes later, the DI says, ‘Mason’s fingerprints are on everything. Let’s break the news.’ He holds open the door for me.

‘Right.’ He sits down. ‘As we expected, your fingerprints were everywhere in that cellar, Mason. You may as well tell us what went on and who else was involved.’

Folding his arms, Mason sits back. ‘I have nothing to say.’

The DI doesn’t falter. ‘I think we should talk about Hollie Hampton.’

Mason looks visibly shocked, but the DI goes on. ‘Did you pay her? Or did she try to buy you off?’

As Mason frowns, the DI goes on. ‘She came to you, didn’t she? She’d found out what her father had got involved in and she knew you were blackmailing him. Maybe she offered you photographs in exchange for releasing him. But you wanted it all, didn’t you? Killing Hollie allowed you to keep her photos and also continue to blackmail her father.’

‘That’s ludicrous.’ But after his earlier performance, it’s impossible to know if Mason’s look of shock is genuine.